1. Field of Invention
The present invention relates generally to optical network systems. More particularly, the present invention relates to systems and methods for allowing the bandwidth in containers to be shared by different users.
2. Description of the Related Art
The demand for data communication services is growing at an explosive rate. Much of the increased demand is due to the fact that more residential and business computer users are becoming connected to the Internet. Furthermore, the types of traffic being carried by the Internet are shifting from lower bandwidth applications towards high bandwidth applications which include packet-based traffic such as voice, video and data carried within an Ethernet frame.
To address the demand for data communication services, the use of optical networks, such as a synchronous optical network (SONET) and a synchronous digital hierarchy (SDH) network, has become more prevalent. The ever-increasing demand for greater bandwidth in SONET and SDH networks has been achieved by increasing line rates using time-division multiplexing (TDM) and transmitting multiple wavelengths through single fibers using dense wave division multiplexing (DWDM).
ITU-T G.709 “Interface for the optical transport network (OTN),” which is incorporated herein by reference in its entirety, describes a next-generation optical network that is capable of providing increased bandwidth over SONET and SDH networks. ITU-T G.709 describes three levels of bandwidth pertaining containers for different optical channel data units (ODUs). Containers, which are effectively payload envelopes, generally carry signals from a client or a user in a substantially bit-transparent manner. The bandwidth associated with each container may be used by only one clock-locked signal or user. An ODU1 container is arranged to carry up to approximately 2.5 Gigabits (G) of data from a user or a customer as a single channel. An ODU2 container is arranged to carry up to approximately 10 G of data from a user, either as one channel of approximately 10 Gigabits per second (Gbps) or as up to four channels of 2.5 Gbps. An ODU3 container is arranged to carry one signal of up to approximately 40 G from a user, or to carry up to four channels of 10 Gbps.
Containers are assigned to users to facilitate the transmission of data from the users to remote sites, e.g., network destinations. As shown in FIGS. 1A and 1B, a first user 102 has a container 114 that only first user 102 may use to send data to remote sites 110. A second user 106 has a container 118 that only second user 106 may use to send data to remote sites 110. Both first user 102 and second user 106 may send up to approximately 2.5 G using ODU1 containers, as indicated in FIG. 1A.
FIG. 2A is a diagrammatic representation of an ODU3 container and the potential channels that may be carried by the container. An ODU3 container 210, which may have an approximately 40 G capacity may, is assigned to a single user may carry a single channel 214 of up to approximately 40 Gbps. Alternatively, ODU3 container 210 may carry up to four channels 218 of up to approximately 10 Gbps that are associated with the single user.
When a container is used to its capacity of close to its capacity, i.e., when substantially all of the bandwidth allocated to a container is effectively used, the assignment of a single user to a container is relatively efficient. However, for instances in which the bandwidth of a container is underutilized, the assignment of a single user to a container may be relatively inefficient. By way of example, as shown in FIG. 2B, when a first container 260 that has an approximately 40 G capacity only carries a single channel 264 of up to approximately 10 Gbps and a second container 280 with an approximately 40 G capacity also only carries a single channel 284 of up to approximately 10 Gbps, each container 260, 280 wastes approximately 30 G of bandwidth. Between first container 260 and second container 280, approximately 60 G are effectively wasted. Wasting up to approximately 60 G of bandwidth may be significant, particularly since there may be other users within an optical network or circuit who would benefit from 60 G of bandwidth.
In general, wasting any amount of bandwidth in a container may be significant. For instance, for an ODU1 container with a capacity of approximately 2.5 G, any amount of the 2.5 G that is not used by the user to which the container is allocated is wasted in that no other user has access to that capacity. Similarly, for an ODU2 container with a capacity of approximately 10 G, any amount of the 10 G that is not used by the user to which the container is allocated is also effectively wasted.
Therefore, what is needed is an efficient method and apparatus for allowing the bandwidth in containers to be shared. That is, what is desired is a system that enables a plurality of users or customers to share the capacity of a container.